From Sea Wolf to Sea Ceptor – the Royal Navy’s defensive shield

In this article, we look at the Sea Wolf missile, and its successor, Sea Ceptor which was formally accepted into RN service in 2018.

The RN’s first missile-killer – Sea Wolf

Sea Wolf began in development began in 1967 and was finally accepted into service in 1979, initially fitted to the Type 22 and some modified Leander frigates. The system was considered the best short-range point defence missile of its time and reputedly intercepted at 4.5” shell in flight during trials. Combat-tested in the 1982 Falklands war, of the 8 missiles fired in anger, it is thought to have achieved 5 aircraft kills. The three Sea-Wolf equipped frigates present never had the opportunity to intercept an Exocet anti-ship missile but acted a ‘goalkeeper’ to the aircraft carriers, providing important defensive reassurance. The weaknesses of the system were primarily due to limitations of radar and computing technology of the time rather than the capabilities of the missile and performance has been considerably evolved over the last 40 years.

The original GWS-25 Conventionally-Launched Seawolf (CLSW) version was manually-loaded into a heavy 7.3-tonne Vickers sextuple launcher which required frequent maintenance and several minutes to reload. Although a lightweight missile, the single-headed CLSW fitted to the Leander class frigates, including fire control radar and computers, had a significant footprint and added a total of 13.5 tonnes to the ship before any rounds were embarked.

As early as 1981, British Aerospace was awarded a £40M contract for the development of the lightweight GWS-26 Mod 2 version for fitting to the Sea-Dart equipped Invincible class carriers and the Batch III Type 42 destroyers. This was based on a 4-barrel launcher designed by Rose Forgrove Ltd weighing just 2.1 tonnes. Vickers also designed a twin-barrelled launcher with automated loading from below, although no prototype was ever built. A smaller Type 911 Mod 3 fire-control radar was also developed and had begun production when the entire lightweight Sea Wolf project was axed as an economy measure as part of the post-Cold War ‘peace dividend’.

The GWS-26 Mod 1 Vertical Launch Seawolf (VLSW) first went to sea in 1990 on board the first Type 23 frigate, HMS Norfolk fitted with a 32-cell silo. Vertically-launched missiles have several advantages over a trainable launcher. As the missile is fired straight upward above the ship’s superstructure there are no blind arcs and the missile can engage targets at 360º. The missiles do not need to be struck down into a magazine in harbour and then and later brought up to the launcher when in action. They are loaded in sealed containers and the full outfit can be fired rapidly if needed. The disadvantages are that the silo is potentially more vulnerable than a magazine deep in the ship and for very close-in engagements, the trainable launcher may be fractionally quicker, allowing direct flight in line of sight to the target. VLS are also very awkward to replenish at sea and no navy has yet to satisfactorily solve this problem. The first VLSW was test-fired in September 1982 and the full £250M production contract was placed in 1984. Vertical launch systems have now almost entirely replaced trainable launchers in modern naval vessels.

  • Sea Wolf Missile

    HMS Cornwall test-fires a Sea Wolf from her aft mounting, April 2009.

  • Sea Wolf missile

    Firing from Cornwall’s forward mounting.

  • HMS St Albans Sea Wolf

    HMS St Albans test-fires Vertical Launch Sea Wolf, Oct 2008.

  • 3rd Sea Wolf away – note the two empty cells to port. The silo has only been loaded with 4 missiles for this trial.

  • Lightweight Sea Wolf

    (Left) Sea Wolf trainable launcher variants. (Right) Lightweight four barrel launcher during test-firing in 1983.

  • (Left) The Type 23 frigate carried two Type 911 Sea Wolf Fire control radars weighing 1.7 tonnes each. Sea Ceptor is cued by the Artisan radar at the masthead which eliminates the need for the fire control radars – they have been replaced by two small platform data link aerials (right).

The original Sea Wolf missile had a speed of around Mach 2, weighed 82kg and had a 14Kg proximity-fused high explosive warhead. The VL has increased range from 6 km to 10 km and the booster motor increased the missile to 3m long and a total weight of 140kg. A turn-over pack using thrust vectoring rapidly rotates the missile from vertical to horizontal when about 30 meters above the ship (a similar system is used by Sea Ceptor). The VLSW canisters are loaded by crane into the ship and their weight is carried by collars that sit on top of the silo.

Sea Wolf is fully automated and initial target detection comes from the Artisan 997 radar. Once launched, guidance is by command line-of-sight from the two dedicated Type 911 Fire Control Radars (FCR). The missile and the target are tracked by the FCR and guidance commands are issued from the ship to the missile via microwave link. Each FCR can control two missiles simultaneously.

All Sea Wolf stocks were upgraded to Block 2 standard from 2005. New fuses incorporating IR and RF sensors were added to improve performance against low signature, low flying targets. A new electronic fin actuation system enhanced manoeuvrability. The £260M Seawolf Mid-Life Update (SWMLU) program began in November 2000 with HMS Sutherland the first ship to be upgraded. The focus was on improved guidance in demanding environments. An Electro-Optic sensor was integrated with the pre-existing ‘I’ and ‘K’ band radars in the Type 911 FCR. The CLSW system passed out of RN service in 2011 with the premature decommissioning of the last Type 22 frigates.

Sea Wolf can be considered a successful programme that has served the RN for more than 40 years. Surprisingly it never really achieved export success and was only adopted by Chile and Brazil for use with ex-RN frigates and for the two Malaysian Lekiu class frigates built by Yarrow in the mid-1990s. Advances in both guidance and missile technology will see Sea Wolf phased out of RN service by 2020 to be replaced by Sea Ceptor. At the time of writing, Sea Wolf remains operational onboard HMS Sutherland, HMS Monmouth and St Albans but is being replaced by Sea Ceptor during the ongoing Type 23 LIFEX refit programme.

A new missile for evolving threats – Sea Ceptor

GWS-35 Sea Ceptor was officially accepted into RN service in May 2018. MBDA (a joint venture between BAE Systems, Leonardo and Airbus – the leading European missile manufacturer) developed Sea Ceptor based on their Common Anti-Air Modular Missile (CAMM). CAMM was the answer to the MoD’s requirement for an affordable modular missile using common parts for use on land, at sea or in the air. The Future Local Area Air Defence System (FLAADS) project aimed to control costs through reuse of existing technology, while delivering weapons that could cope with high-speed, hard-manoeuvring modern threats. The British Army is replacing its Rapier air defence missile with CAMM (known as Sky Sabre) while CAMM technology has been used to upgrade the Advanced Short Range Air-to-Air Missile (ASRAAM) for the RAF.

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CAMM incorporates the tail fin control technology and rocket motor from ASRAMM. The blast-fragmentation warhead is derived from the Meteor Beyond Visual Range Air-Air Missile that entered service with the RAF last year. Some internal electronics from the Sea Wolf Block 2 missiles are also incorporated. Otherwise, Sea Ceptor has little in common with Sea Wolf, Weighing 99kg and 3.3m in length, it is considerably bigger and capable of Mach 3. Most significantly it has far greater range, officially capable of interceptions between 1 and 25km, although the missile reportedly travelled up to 60 km during trials. This has important tactical implications. Sea Wolf provided point-defence for the ship itself and a few others in close company, Sea Ceptor can now defend more than 1,000 km² around the ship, offering an area air defence capability. This will allow the frigates to operate in more loose formation with the aircraft carrier or high-value Unit, important for anti-submarine operations, while still contributing to the air defence.

As the air threat to surface ships has evolved with increasing speed and sophistication, being able to intercept faster and at a greater distance becomes imperative. The ability to make high-G manoeuvres in the terminal phase and better resistance against jamming are all important improvements over Sea Wolf but it is the guidance system that is greatest step-change. CAMM / Sea Ceptor utilises the powerful track-while-scan ability of the multi-function Artisan 3D radar. Artisan has a maximum range of about 200km and can detect small object travelling at Mach 3 more than 25km away. It can track up to 800 objects simultaneously and is highly resistant to ECM and interference. Artisan provides initial target data to Sea Ceptor and updates the missile in flight via the two-way Platform Data Link Terminal (PDLT). Most importantly, the missile itself has an advanced active radar seeker head for use in the terminal phase which removes the need for dedicated fire control radars. Numbers are classified but it is clear that a salvo of missiles could be launched simultaneously against multiple targets.

Sea Ceptor is clearly optimised for defending against saturation anti-ship missile attacks, which could overwhelm the limitations of legacy systems based on target illumination fire-control radars.

CAMM features another major innovation, soft vertical launch (SVL). A very rapid chemical reaction in a gas generator in the base of the missile canister ejects the missile out of the tube via a piston with enough momentum to get about 30m above the ship. Small lateral thrusters then fire in sequence to turn the missile horizontal before the main rocket motor ignites. This ‘cold-launch’ method reduces the heat signature and has a better minimum intercept range, compared to conventional VLS which have a greater turnover arc. It also reduces stress on the vessel’s structure and avoids the risks of a missile with a burning rocket motor jammed in its cell. SVL also saves smoke and exhaust gas efflux enveloping the ship which can lower visibility for several minutes in light winds.

  • ‘The mushroom farm’. The 32-cell silo on HMS Argyll. Note how each cell is offset from the vertical. If the rocket motor should fail to ignite after the soft-launch, the missile will not fall on the ship. Sea Ceptor is longer than the Sea Wolf the silo was designed for, so each cell protrudes above the silo top slightly.

  • MBDA image of the missile

  • The launch sequence. (1) Cold ejection from silo. (2) First lateral turnover thruster fires. (3-4) Other thrusters fire briefly to balance and orientate the missile. (5) Now horizontal, the main rocket motor ignites. (6) Rapid acceleration to target.

  • HMS Argyll demonstrates salvo firing with the launch of two missiles simultaneously during trials at the MoD Hebrides Range, October 2017.

  • Sea Ceptor Quad Pack Mk41

    (Left) CGI of Quad-packed Sea Ceptor launch from Mk41 Extensible Launching System. (Centre) Successful Sea Ceptor test-launch from Mk 41. (Right) The munitions adapter that fits inside the Mk41 cell aligns the 4 missiles and provides shock-mitigation

  • Former Defence Secretary, Gavin Williamson inspects CAMM being made at MBDA’s newly built manufacturing facility at Bolton, Lancashire, July 2018.

  • Artisan (Advanced Radar Target Indication Situational Awareness and Navigation) Type 997 medium-range air and surface surveillance 3D radar carried on the mainmast of the Type 23. Said to be around five times more effective than its Type 996 predecessor, its enhanced capabilities are critical to Sea Ceptor guidance. The RN has purchased 19 sets fitted to the frigates, LPDs and the aircraft carriers.

  • (Left) The Sea Ceptor command and control cabinets (HMS Westminster) fit into space formerly occupied by the Sea Wolf computers with space to spare/ (Right) Missile Silo and forward PDLT on HMS Montrose.

  • Overhead view of the Type 26 frigate shows the positioning of the missile silos. There are two 24-cell Sea-Ceptor silos. One forward, behind the gun and one aft, behind the funnel and above the mission bay.

The cost of upgrading the Type 23 frigates missiles has been kept down by using the existing ship footprint and infrastructure as far as possible. The existing Silo has been used, although modified to take the longer missile. The main weight of the cells is carried on shock-proof mountings by the deck below, instead of the silo top in the case of Sea Wolf. The deck has been strengthened to cope with the shock loadings generated at launch. The removal of the Fire Control Radars and replacement by the small PDLT is a considerable saving in top-weight. This reduces the stress on the ship or could be used as a growth margin to fit additional equipment on the superstructure. There are four launch management system cabinets, one for every eight missiles and other below-decks control equipment in the operations room and in the old Sea Wolf radar offices. Overall the amount of equipment is reduced and some of the existing cabling has been re-used.

The delivery of Sea Ceptor into service has been relatively quick. MBDA invested around £2 Billion in its development and were rewarded with a £483M demonstration contract for Sea Ceptor in January 2012. To reduce costs, development and de-risking work was carried out entirely on land and benefited from the Type 997 (Artisan) radar already proven in service. Missile test firings were conducted at the Vidsel range in Sweden while Integration and development was done in Bristol, Stevenage and at the Type 23 Land Based Test Site (LBTS) at Portsdown Technology Park. A further £250M contract to supply the equipment for the frigates was signed in September 2013. The number of missiles purchased, their individual cost and their delivery schedule are not in the public domain

Sea Ceptor will be fitted to the Type 26 frigates which will carry up to 48 missiles in two separated 24-cell silos. It is also very likely that the Type 31e frigates will carry the system, although with a smaller number of cells. It is expected that Artisan radars and the control equipment will be transferred to the new frigates from the Type 23s as they decommission. While the system has been fully proven and de-risked, there are integration and timing challenges that will be involved with this migration process.

A flexible friend

It is possible the Type 45 destroyers could be fitted with Sea Ceptor. Their Sylver VLS cells that hold Aster 15/30 (Sea Viper) missiles could be adapted with quad packs that allow 4 CAMM to fit inside each cell. Theoretically, a Type 45 could, for example, be outfitted with 30 x long-range Aster30 and 72 x quad-packed Sea Ceptor. Trading 18 x Aster15 for 72 x Sea Ceptor would make sense and add significantly to each ship’s firepower. Sea Ceptor uses around 70% of the same technology as the PAAMS carried by the Type 45, so integration should be fairly straight forward. The Sampson radar offers even better performance than Artisan, potentially offsetting the reduced range and performance of Sea Ceptor compared with Aster15. Quad-packed Sylver is a theoretical niche capability for the UK and France but Lockheed Martin has already tested and proven the quad-pack concept for their Mk 41 VLS Extensible Launching System (EXLS). Mk 41 is utilised by many navies across the world and Sea Ceptor is an attractive proposition for cost-effective medium-range naval air defence. (It’s an unlikely scenario but a single Type 26 frigate could potentially carry a total of 144 Sea Ceptor missiles if also quad-packed into its 24 x Mk 41 cells!)

CAMM are assembled in Bolton, Lancashire, although the component supply chain is global. MBDA is a European company but CAMM is primarily a British product and already something of an export success. Lockheed Martin Canada is fitting Sea Ceptor to the New Zealand Navy’s ANZAC Frigates as part of a major Systems Upgrade (FSU) project. Chile has also contracted LM Canada to upgrade their ex-RN Type 23 frigates and they will receive the system. Brazil has selected Artisan and a 12-cell Sea Ceptor installation for its Tamandaré class corvettes being constructed by TKMS in Germany. The Royal Navy, New Zealand and Chilean navies have now established a ‘Sea Ceptor users group’ to share experience and best practice with the system.

CAMM/Sea Ceptor appears to be a rare example of a highly successful UK procurement project, affordable, delivered on time and meeting all requirements. Through its acquisition, the RN has quietly gained a step-change in defensive capability, which is very much needed in the face of ever more demanding air and missile threats. Operating inside the Sea Viper umbrella of the Type 45 destroyers, the frigates can provide the next line of defence for the carrier battle group with an equally credible weapon system.